This invention relates to a luminaire having a reflector which mixes light from a multi-color array of LEDs, and more particularly to a spotlight which generates white light from such an array.
The standard light source for small to moderate size narrow beam lighting for accent lighting and general illumination is the incandescent/halogen bulb, such as a PAR (parabolic aluminized reflector) lamp. These sources are compact and versatile, but they are not very efficient. A given lamp operates at a given color temperature for a fixed power, and while they are dimmable, the color temperature shifts with applied power according to the blackbody law, which may or may not be the variation that the user desires.
An array of LEDs in a each of a plurality of colors offers the possibility of creating a luminaire in which the color temperature may be controlled at any power level, thereby enabling lamp which is dimmable and emits a uniformly white light at any power level.
The English language abstract of JP-A-06 237 017 discloses a polychromatic light emitting diode lamp having a 3.times.3 array of light emitting diodes of two types, a first type having elements for emitting red light and blue light, and a second type having elements for emitting red light and green light. The stated object is to mix colors so that the mixed color would be recognized as the same color in any direction, but there are no optical provisions to facilitate mixing. It is simply a two-dimensional array of LEDs in a lamp case filled with resin, which would do little more than provide some diffusion.
WO 98/16777 discloses a signal lamp having an array of LEDs in a single color for the purpose of signaling, e.g. a traffic light. A rotationally symmetric housing surrounds the array, but diverges so that the light from the LEDs is transmitted to a collimating Fresnel lens without reflection. If the single-color LEDs were replaced by a multi-colored array, the lens would image the individual LEDs without mixing the colors.